The greening of airport aprons and taxiways gathers pace as industry and airlines seek new ways to reduce engine power
TaxiBot undergoing tests (photo: IAI)
Mon 26 Nov 2012 – After four years in development, Israel Aerospace Industries (IAI) and Airbus have unveiled to airlines the TaxiBot semi-robotic pilot controlled vehicle that is designed to transport aircraft from the gate to the runway without using engine power during taxiing and so saving fuel and emissions. The two partners estimate taxiing will cost airlines around $8.5 billion in annual fuel costs by the end of the decade, which could be reduced to less than $3 billion through TaxiBot operations. They calculate this represents a potential reduction of around 20 million tonnes of CO2 emissions. There is growing awareness from both airlines and airports in the potential for reducing fuel and emissions from aircraft taxiing and KLM is the latest to express interest in WheelTug’s onboard electric drive system that negates the need for aircraft engine power or tugs for pushback and taxi operations. Two other collaborations are also working on similar solutions to help save fuel, emissions and noise at airports.
Last week, IAI and Airbus conducted live demonstrations of a TaxiBot vehicle to invited airlines and ground handlers at Chateauroux Airport in France. From the cockpit of an Airbus A320, airline pilots carried out a series of driving and control tests to evaluate the vehicle.
Although the long-term plan is for the TaxiBot to be used for both taxiing out and taxiing in, for the time being its use will be confined to taxiing out purposes. The vehicle requires an operator inside the vehicle, who pushes back the aircraft from the gate and eventually returns the vehicle to the apron. Otherwise, the pilot is given total control in manoeuvring the aircraft towards the runway before the engines are started approximately three to five minutes before take-off.
Simulations and studies conducted by IAI show that minor or no modifications are required by airports to cater for the TaxiBot, which uses hybrid diesel electric power to transport the airplane, and there is no overall impact on taxiing time when operating a mix of aircraft taxiing with and without the TaxiBot.
Initially, IAI will focus on a vehicle for narrowbody aircraft, which Shuki Eldar, the company’s VP Business Development, says should enter the market at the end of 2013 or early 2014, with a widebody version about a year later. Eldar estimates the price will be in the region of $1.5 million for the narrowbody TaxiBot and double that for the widebody version. Production of the narrowbody vehicle is being initiated at TLD France, a leading manufacturer of airport ground support equipment. IAI’s TaxiBot Project Director Ran Braier says there has been considerable interest in the TaxiBot from Chinese airlines and the vehicles could also be manufactured in China, where TLD already has two facilities.
To achieve Boeing 737 certification, which is expected by mid-2013, testing on a Lufthansa Boeing 737 aircraft will start next year and Lufthansa LEOS, the airline group’s ground handling company, will then trial actual day-to-day operations at Frankfurt Airport with three new TaxiBots. Airbus A320 family certification is anticipated at the beginning of 2014.
IAI and Airbus estimate typical fuel consumption for a Boeing 747 on a 17-minute taxi before take-off is in the region of one tonne of fuel, emitting nearly 3.2 tonnes of CO2. In comparison, the TaxiBot consumes only 25 to 30 litres of fuel. By minimising the use of aircraft engines, a significant amount of noise at airports and the surrounding area is reduced.
Braier says the vehicle will be of interest to airlines at large airports, particularly in Europe where there are environmental controls in place, but he foresees that ten years from now saving fuel and reducing the environmental footprint will be a major consideration in many countries throughout the world. Shuki Eldar believes that the carbon emission reductions achieved by TaxiBot operations could help potential buyers in developing countries purchase the TaxiBot through UN green climate fund grants.
WheelTug has taken a different route to the concept of engine-free taxiing by using high-performance electric motors installed in the nose gear wheels of an aircraft to provide full mobility while on the ground. While averting the need for a vehicle, the onboard system adds weight to the aircraft and therefore extra fuel use in flight but this can be offset by faster turnaround times and an 80% reduction in ground operation fuel consumption, claims WheelTug. It estimates a taxiing Boeing 737 burns 24 to 27 pounds (10.9-12.2kg) of fuel per minute, whereas the WheelTug system uses only four pounds because it is electrically powered by the aircraft’s auxiliary power unit (APU).
The company estimates total savings of over $500,000 per aircraft per year and although it does not specify a cost price at present, systems will be offered to airlines entirely on a lease or power-by-the-hour basis, so avoiding capital expenditure to customers. Initially, the system is being developed for narrowbody Boeing 737NG and Airbus A320 aircraft.
In May, Alitalia became the launch customer when it signed an agreement to install WheelTug systems on 100 of the airline’s A320 aircraft. Earlier in the year WheelTug signed Letters of Intent (LOI) with Israir Airlines for 10 systems for its A320 fleet and also a leasing arrangement with Jet Airways for the Indian carrier’s 737NG aircraft. Other LOIs have been signed with El Al and Onur Air, and two weeks ago an LOI was signed with KLM, with a definitive agreement subject to certification of the system. WheelTug says it now has 258 aircraft delivery slots allocated for the system.
Following a short collaboration between the two companies, WheelTug and Parker Aerospace’s Aircraft Wheel & Brake Division have entered into a MoU agreement whereby Parker will be the exclusive supplier of wheels for the system on Boeing 737NG and Airbus A320 aircraft. Certification is planned for the fourth quarter of 2013.
Two other collaborations are looking to use an aircraft’s onboard electrical system to power aircraft to and from the runway without the use of main engines or a tug.
Aerospace manufacturers Safran and Honeywell are developing the Electric Green Taxiing System with support from low-cost airline easyJet. Testing has already started using an Airbus A320 at Montpellier Airport in France and earlier this year the partners said they were expecting to start operational trials in 2013 and are looking to offer the system either on new aircraft or as a retrofit solution to in-service aircraft by 2016. EasyJet’s involvement will help establish whether the estimated savings in fuel and emissions can be realised and will also quantify other benefits. The airline will also assist in establishing the standard operational procedures for aircraft equipped with the system.
US aerospace companies Crane and L-3 announced in July an agreement to develop and market the GreenTaxi electric taxi system. The technology has already been demonstrated at Frankfurt Airport in December 2011 using an Airbus A320 in taxi and manoeuvre tests in which speeds of up to 30 kilometres per hour were achieved in varying runway conditions. It was conducted by a team led by L-3’s Magnet-Motor division and included Lufthansa German Airlines, Lufthansa Technik and the Frankfurt Airport Operating Authority, Fraport, with additional support from Airbus.